Organic chemicals used to produce numerous industrial products, such as paints, solvents, synthetic fibers and plastics, currently are synthesized primarily from petroleum-based products. Moreover, the major portion of pharmaceuticals and fine chemicals also are manufactured from petroleum-derived organic chemicals. Indeed, of the more than one hundred million tons of fine, specialty, intermediate and commodity chemicals produced annually in the United States, only ten percent of these chemicals are biobased, i.e., produced from renewable resources. Committee on Biobased Industrial Products, Biobased Industrial Products: Research and Commercialization Priorities, National Academies Press: Washington, D.C., 1999, pp. 17,18. There is an increasing need to replace petroleum-derived chemicals with chemicals derived from renewable resources.
Unsaturated compounds, such as alkenes (which also are referred to herein as olefins), are particularly important chemical feedstocks for producing various products, including polyethylene, polypropylene and polybutylene polymers. The properties of such polymers are modified by copolymerization with different unsaturated chemicals. For example, linear low-density polyethylene (LLDPE) is produced by copolymerizing ethylene and 1-octene. Known processes for producing 1-octene from petroleum-based sources, such as Fischer-Tropsch processes or SHOP-type ethylene oligomerization processes, are inefficient and result in mixtures of oligomerization products that are produced in statistical proportions. Hence, large quantities of undesired materials are produced. As a result, there currently is a shortage of 1-octene, and LLDPE production is constrained by the limited supply of 1-octene.
A further disadvantage associated with current processes is that pollutants are released during extraction and processing of coal and petroleum, posing a number of potential hazards to the environment and human health. Thus, in addition to economic influences, increasing environmental and health concerns provide an impetus for developing biobased products from renewable resources to replace petroleum-based products.
A potential method for forming unsaturated industrial chemicals is metathesis chemistry. Metathesis often involves reacting two different compounds by interchanging atoms or groups of atoms between two molecules. The olefin metathesis reaction can be thought of as a reaction in which carbon-carbon double bonds in an olefin are broken and rearranged in a statistical fashion. An example of alkene metathesis is illustrated in Scheme 1.
In recent years, with the development of new, well-defined, functional group-tolerant metathesis catalysts, metathesis chemistry has been applied to polymer chemistry and complex total syntheses. See, for example, Fürstner, A. Olefin Metathesis and Beyond. Angew. Chem., Int. Ed. Engl. 2000, 39, 3012-3043.
Newman et al., PCT publication number WO 02/076920 (Newman), disclose a process for metathesis of unsaturated fatty acid esters or unsaturated fatty acids with small chain olefins. Newman discloses “contacting an unsaturated fatty acid ester or an unsaturated fatty acid . . . with ethylene in the presence of a metathesis catalyst . . . ” Newman, page 5, line 22-24. Newman states that in a “most preferred embodiment related thereto, the unsaturated fatty acid is oleic acid; the lower olefin is ethylene; and the olefinic metathesis products include 1-decene and 9-decenoic acid.” Newman, page 5, line 32-page 6, line 2. Newman does not, however, disclose any method for isomerizing fatty acids or fatty acid derivatives, nor does Newman teach conjugated linoleic acid or a method for its production. Newman also does not disclose making 1-octene.
Thus, for the reasons stated above, new methods for converting renewable resources into industrial chemicals, such as 1-octene, are desired.